U.S. patent application number 14/542274 was filed with the patent office on 2015-10-22 for exhaust valve for engine.
This patent application is currently assigned to Hyundai Motor Company. The applicant listed for this patent is Hyundai Motor Company. Invention is credited to Hongkil BAEK, Bokyung KIM, Jiho KIM, Seungwoo LEE, Inwoong LYO, Jiyoun SEO.
Application Number | 20150300215 14/542274 |
Document ID | / |
Family ID | 54249859 |
Filed Date | 2015-10-22 |
United States Patent
Application |
20150300215 |
Kind Code |
A1 |
BAEK; Hongkil ; et
al. |
October 22, 2015 |
EXHAUST VALVE FOR ENGINE
Abstract
An exhaust valve for an engine which discharges an exhaust gas
generated in a combustion chamber of the engine may include an
adiabatic coating layer having a polyamideimide resin and an
aerogel dispersed in the polyamideimide resin and having thermal
conductivity of 0.60 W/m or less formed on a face portion of the
exhaust valve coming into contact with a flame.
Inventors: |
BAEK; Hongkil; (Seoul,
KR) ; KIM; Bokyung; (Yongin-si, KR) ; LEE;
Seungwoo; (Seoul, KR) ; KIM; Jiho; (Seoul,
KR) ; LYO; Inwoong; (Suwon-si, KR) ; SEO;
Jiyoun; (Suwon-si, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Hyundai Motor Company |
Seoul |
|
KR |
|
|
Assignee: |
Hyundai Motor Company
Seoul
KR
|
Family ID: |
54249859 |
Appl. No.: |
14/542274 |
Filed: |
November 14, 2014 |
Current U.S.
Class: |
60/324 |
Current CPC
Class: |
F01L 3/04 20130101 |
International
Class: |
F01L 3/04 20060101
F01L003/04 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 18, 2014 |
KR |
10-2014-0046905 |
Claims
1. An exhaust valve for an engine, which discharges an exhaust gas
generated in a combustion chamber of the engine comprising: an
adiabatic coating layer including a polyamideimide resin and an
aerogel dispersed in the polyamideimide resin and having thermal
conductivity of 0.60 W/m or less formed on a face portion of the
exhaust valve coming into contact with a flame.
2. An exhaust valve for an engine, which discharges an exhaust gas
generated in a combustion chamber of the engine, comprising an
adiabatic coating layer including a polyamideimide resin and an
aerogel dispersed in the polyamideimide resin and having thermal
conductivity of 0.60 W/m or less formed on a neck portion of the
exhaust valve coming into contact with the exhaust gas.
3. An exhaust valve for an engine, which discharges an exhaust gas
generated in a combustion chamber of the engine, comprising an
adiabatic coating layer including a polyamideimide resin and an
aerogel dispersed in the polyamideimide resin and having thermal
conductivity of 0.60 W/m or less formed on a face portion of the
exhaust valve coming into contact with a flame and a neck portion
of the exhaust valve coming into contact with the exhaust gas.
4. The exhaust valve for the engine of claim 1, wherein the
adiabatic coating layer has a thermal capacity of 1,250 KJ/m.sup.3
K or less.
5. The exhaust valve for the engine of claim 1, wherein the
polyamideimide resin exists in a content of 2 wt % or less in the
aerogel.
6. The exhaust valve for the engine of claim 1, wherein the
polyamideimide resin does not exist at a depth corresponding to 5%
or more of a longest diameter from a surface of the aerogel.
7. The exhaust valve for the engine of claim 1, wherein each
aerogel has porosity of 92% to 99% while being dispersed in the
polyamideimide resin.
8. The exhaust valve for the engine of claim 1, wherein the
adiabatic coating layer has a thickness of 50 .mu.m to 500
.mu.m.
9. The exhaust valve for the engine of claim 1, wherein the
adiabatic coating layer includes 5 to 50 parts by weight of the
aerogel based on 100 parts by weight of the polyamideimide
resin.
10. The exhaust valve for the engine of claim 2, wherein the
adiabatic coating layer has a thermal capacity of 1,250 KJ/m.sup.3
K or less.
11. The exhaust valve for the engine of claim 2, wherein the
polyamideimide resin exists in a content of 2 wt % or less in the
aerogel.
12. The exhaust valve for the engine of claim 2, wherein the
polyamideimide resin does not exist at a depth corresponding to 5%
or more of a longest diameter from a surface of the aerogel.
13. The exhaust valve for the engine of claim 2, wherein each
aerogel has porosity of 92% to 99% while being dispersed in the
polyamideimide resin.
14. The exhaust valve for the engine of claim 2, wherein the
adiabatic coating layer has a thickness of 50 .mu.m to 500
.mu.m.
15. The exhaust valve for the engine of claim 2, wherein the
adiabatic coating layer includes 5 to 50 parts by weight of the
aerogel based on 100 parts by weight of the polyamideimide
resin.
16. The exhaust valve for the engine of claim 3, wherein the
adiabatic coating layer has a thermal capacity of 1,250 KJ/m.sup.3
K or less.
17. The exhaust valve for the engine of claim 3, wherein the
polyamideimide resin exists in a content of 2 wt % or less in the
aerogel.
18. The exhaust valve for the engine of claim 3, wherein the
polyamideimide resin does not exist at a depth corresponding to 5%
or more of a longest diameter from a surface of the aerogel.
19. The exhaust valve for the engine of claim 3, wherein each
aerogel has porosity of 92% to 99% while being dispersed in the
polyamideimide resin.
20. The exhaust valve for the engine of claim 3, wherein the
adiabatic coating layer has a thickness of 50 .mu.m to 500 .mu.m
and wherein the adiabatic coating layer includes 5 to 50 parts by
weight of the aerogel based on 100 parts by weight of the
polyamideimide resin.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] The present application claims priority to Korean Patent
Application No. 10-2014-0046905 filed Apr. 18, 2014, the entire
contents of which is incorporated herein for all purposes by this
reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] An exemplary embodiment of the present invention relates to
an engine for a vehicle, and more particularly, to an exhaust valve
discharging an exhaust gas generated in a combustion chamber.
[0004] 2. Description of Related Art
[0005] Generally, an internal combustion engine refers to an engine
where a fuel gas generated by combusting fuel directly acts to a
piston, a turbine blade, or the like to convert heat energy of the
fuel into mechanical work.
[0006] In many cases, the internal combustion engine refers to a
reciprocal motion type engine which ignites a mixture gas of the
fuel and air in a cylinder to cause an explosion and thus move a
piston, but a gas turbine, a jet engine, a rocket, and the like are
also the internal combustion engine.
[0007] The internal combustion engine is classified into a gas
engine, a gasoline engine, a petroleum engine, a diesel engine, and
the like by the used fuel. The petroleum, gas, and gasoline engines
cause ignition by an electric flame by a spark plug, and the diesel
engine sprays the fuel into air at high temperatures and high
pressure to cause spontaneous ignition. There are four and two
stroke cycle methods according to a stroke and an operation of the
piston.
[0008] Typically, it is known that the internal combustion engine
of a vehicle has heat efficiency of about 15% to 35%, about 60% or
more of total heat energy is consumed due to heat energy emitted to
the outside through a wall of the internal combustion engine, an
exhaust gas, and the like even at maximum efficiency of the
internal combustion engine.
[0009] As described above, if a quantity of heat energy emitted to
the outside through the wall of the internal combustion engine is
reduced, efficiency of the internal combustion engine may be
increased, and therefore methods of installing an adiabatic
material outside the internal combustion engine, changing a portion
of a material or a structure of the internal combustion engine, or
developing a cooling system of the internal combustion engine are
used.
[0010] Particularly, if emission of heat generated in the internal
combustion engine through the wall of the internal combustion
engine to the outside is minimized, efficiency of the internal
combustion engine and fuel efficiency of the vehicle may be
improved, but research for an adiabatic material, an adiabatic
structure, or the like, which may be maintained over a long period
of time in the internal combustion engine to which a repeated high
temperature and high pressure condition is applied, has made
insignificant progress.
[0011] The information disclosed in this Background of the
Invention section is only for enhancement of understanding of the
general background of the invention and should not be taken as an
acknowledgement or any form of suggestion that this information
forms the prior art already known to a person skilled in the
art.
BRIEF SUMMARY
[0012] Various aspects of the present invention are directed to
providing an exhaust valve for an engine, which is capable of
ensuring high temperature durability and reducing heat energy
emitted to the outside by applying an adiabatic coating layer
securing high mechanical properties and heat resistance while
having low thermal conductivity and a low volume thermal capacity,
thereby improving efficiency of an engine and fuel efficiency of a
vehicle.
[0013] According to various aspects of the present invention, an
exhaust valve for an engine, which discharges an exhaust gas
generated in a combustion chamber of the engine, may include an
adiabatic coating layer including a polyamideimide resin and an
aerogel dispersed in the polyamideimide resin and having thermal
conductivity of 0.60 W/m or less formed on a face portion of the
exhaust valve coming into contact with a flame.
[0014] According to various aspects of the present invention an
exhaust valve for an engine, which discharges an exhaust gas
generated in a combustion chamber of the engine, may include an
adiabatic coating layer including a polyamideimide resin and an
aerogel dispersed in the polyamideimide resin and having thermal
conductivity of 0.60 W/m or less formed on a neck portion of the
exhaust valve coming into contact with the exhaust gas.
[0015] According to various aspects of the present invention an
exhaust valve for an engine, which discharges an exhaust gas
generated in a combustion chamber of the engine, may include an
adiabatic coating layer including a polyamideimide resin and an
aerogel dispersed in the polyamideimide resin and having thermal
conductivity of 0.60 W/m or less formed on a face portion of the
exhaust valve coming into contact with a flame and a neck portion
of the exhaust valve coming into contact with the exhaust gas.
[0016] The adiabatic coating layer may have a thermal capacity of
1,250 KJ/m.sup.3 K or less.
[0017] The polyamideimide resin may exist in a content of 2 wt % or
less in the aerogel.
[0018] The polyamideimide resin may not exist at a depth
corresponding to 5% or more of a longest diameter from a surface of
the aerogel.
[0019] Each aerogel may have porosity of 92% to 99% while being
dispersed in the polyamideimide resin.
[0020] The adiabatic coating layer may have a thickness of 50 .mu.m
to 500 .mu.m.
[0021] The adiabatic coating layer may include 5 to 50 parts by
weight of the aerogel based on 100 parts by weight of the
polyamideimide resin.
[0022] According to various embodiments of the present invention,
it is possible to ensure high temperature durability and reduce
heat energy emitted to the outside by applying an adiabatic coating
layer securing high mechanical properties and heat resistance while
having low thermal conductivity and a low volume thermal capacity,
thereby improving efficiency of an engine and fuel efficiency of a
vehicle.
[0023] Further, in various embodiments of the present invention, it
is possible to secure high temperature durability and reduce a
manufacturing cost by reducing a valve temperature, without using a
very costly high heat resistant material (inconel and the like)
where a nickel (Ni) content is increased.
[0024] It is understood that the term "vehicle" or "vehicular" or
other similar terms as used herein is inclusive of motor vehicles
in general such as passenger automobiles including sports utility
vehicles (SUV), buses, trucks, various commercial vehicles,
watercraft including a variety of boats and ships, aircraft, and
the like, and includes hybrid vehicles, electric vehicles, plug-in
hybrid electric vehicles, hydrogen-powered vehicles and other
alternative fuel vehicles (e.g., fuel derived from resources other
than petroleum). As referred to herein, a hybrid vehicle is a
vehicle that has two or more sources of power, for example, both
gasoline-powered and electric-powered vehicles.
[0025] The methods and apparatuses of the present invention have
other features and advantages which will be apparent from or are
set forth in more detail in the accompanying drawings, which are
incorporated herein, and the following Detailed Description, which
together serve to explain certain principles of the present
invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] FIG. 1 is a view schematically illustrating an exemplary
exhaust valve for an engine according to the present invention.
[0027] FIG. 2 is a picture illustrating a surface of an adiabatic
coating layer obtained in the exemplary exhaust valve for the
engine according to the present invention.
[0028] FIG. 3 is a picture illustrating a surface of a coating
layer obtained in a Comparative Example as compared to the
exemplary exhaust valve for the engine according to the present
invention.
[0029] It should be understood that the appended drawings are not
necessarily to scale, presenting a somewhat simplified
representation of various features illustrative of the basic
principles of the invention. The specific design features of the
present invention as disclosed herein, including, for example,
specific dimensions, orientations, locations, and shapes will be
determined in part by the particular intended application and use
environment.
DETAILED DESCRIPTION
[0030] Reference will now be made in detail to various embodiments
of the present invention(s), examples of which are illustrated in
the accompanying drawings and described below. While the
invention(s) will be described in conjunction with exemplary
embodiments, it will be understood that the present description is
not intended to limit the invention(s) to those exemplary
embodiments. On the contrary, the invention(s) is/are intended to
cover not only the exemplary embodiments, but also various
alternatives, modifications, equivalents and other embodiments,
which may be included within the spirit and scope of the invention
as defined by the appended claims.
[0031] Throughout the specification, unless explicitly described to
the contrary, the word "comprise" and variations such as
"comprises" or "comprising", will be understood to imply the
inclusion of stated elements but not the exclusion of any other
elements.
[0032] In addition, the terms " . . . unit", " . . . means", " . .
. part", and " . . . member" described in the specification mean
units of comprehensive constitutions for performing at least one
function and operation.
[0033] FIG. 1 is a view schematically illustrating an exhaust valve
for an engine according to various embodiments of the present
invention.
[0034] Referring to FIG. 1, an exhaust valve 100 for an engine
according to the various embodiments of the present invention may
be applied to an engine for vehicles, which ignites and explodes a
mixture gas of a fuel and air in a cylinder to move a piston.
[0035] For example, the exhaust valve 100 for the engine according
to various embodiments of the present invention may be applied to a
turbo engine where a temperature of an exhaust gas is high.
[0036] The exhaust valve 100 for the engine is a matter for
exhausting the exhaust gas generated in a combustion chamber of the
cylinder, and includes a stem portion 11, a face portion 13, and a
neck portion 15.
[0037] Herein, the stem portion 11 may be defined as a portion
coming into contact with a valve guide and the like, the face
portion 13 may be defined as a portion coming into contact with a
flame of the combustion chamber, and the neck portion 15 may be
defined as a portion coming into contact with the stem portion 11
and the face portion 13 and coming into contact with the exhaust
gas.
[0038] Hereinafter, application of the exhaust valve 100 according
to the various embodiments of the present invention to an engine of
a vehicle will be described as an example, but it should be
understood that the protection scope of the present invention is
not essentially limited thereto, and as long as the exhaust valve
is an exhaust valve adopted in various kinds of internal combustion
engines for the various purposes, such as a gas turbine, a jet
engine, and a rocket, the technical spirit of the present invention
may be applied thereto.
[0039] The exhaust valve 100 for the engine according to various
embodiments of the present invention has a structure which can
ensure high temperature durability and reduce heat energy emitted
to the outside by applying an adiabatic coating layer securing high
mechanical properties and heat resistance while having low thermal
conductivity and a low volume thermal capacity, thereby improving
efficiency of an engine and fuel efficiency of a vehicle.
[0040] That is, various embodiments of the present invention
provide the exhaust valve 100 for the engine, which can secure high
temperature durability by reducing a valve temperature, without
using a very costly high heat resistant material (inconel and the
like) where a nickel (Ni) content is increased.
[0041] To this end, in the exhaust valve 100 for the engine
according to various embodiments of the present invention, the
adiabatic coating layer 50 is formed on the face portion 13 coming
into contact with the flame. That is, the adiabatic coating layer
50 is a bottom surface of the valve, and may be formed on the face
portion 13 coming into contact with the flame of the combustion
chamber of the cylinder.
[0042] Moreover, in the exhaust valve 100 for the engine according
to various embodiments of the present invention, the adiabatic
coating layer 50 is formed on the neck portion 15 coming into
contact with the exhaust gas.
[0043] Herein, the adiabatic coating layer 50 may be formed on any
one of the face portion 13 and the neck portion 15, and may be
formed on both the face portion 13 and the neck portion 15.
[0044] Hereinafter, the adiabatic coating layer 50 applied to the
exhaust valve 100 for the engine according to various embodiments
of the present invention, and an adiabatic coating composition
thereof will be described in more detail.
[0045] Various embodiments of the present invention provide the
adiabatic coating composition including a polyamideimide resin
dispersed in a high boiling point organic solvent or an aqueous
solvent and an aerogel dispersed in a low boiling point organic
solvent as the adiabatic coating layer.
[0046] Further, the adiabatic coating layer according to various
embodiments of the present invention includes the polyamideimide
resin and the aerogel dispersed in the polyamideimide resin, and
has thermal conductivity of 0.60 W/m or less.
[0047] According to various embodiments of the present invention,
the adiabatic coating composition including the polyamideimide
resin dispersed in the high boiling point organic solvent or the
aqueous solvent and the aerogel dispersed in the low boiling point
organic solvent may be provided.
[0048] The present inventors confirmed through an experiment that
the coating composition obtained by dispersing the polyamideimide
resin and the aerogel in predetermined solvents, respectively and
then mixing the resultant solutions, and the coating layer obtained
therefrom could secure high mechanical properties and heat
resistance while having lower thermal conductivity and low density,
and are applied to the internal combustion engine to reduce heat
energy emitted to the outside and thus improve efficiency of the
internal combustion engine and fuel efficiency of the vehicle,
thereby accomplishing the invention.
[0049] Moreover, the present inventors confirmed through an
experiment that the aforementioned coating layer could be applied
to a portion of the exhaust valve 100 or the entire exhaust valve
100, which was a part of the internal combustion engine, to secure
high temperature durability by reducing a valve temperature,
without using the very costly high heat resistant material where
the nickel (Ni) content was increased, thereby accomplishing the
invention.
[0050] Recently, methods of using the aerogel (or air-gel) have
been introduced in fields such as an adiabatic material, an impact
limiter, or a soundproofing material. This aerogel has a structure
formed by entangling microfilaments having a thickness that is a
ten-thousandth of that of hair, and has porosity of 90% or more,
and main materials thereof are silicon oxide, carbon, or an organic
polymer. Particularly, the aerogel is an ultra-low density material
having high translucency and ultra-low thermal conductivity due to
the aforementioned structural characteristic.
[0051] However, since the aerogel is easily broken by small impact
due to high brittleness to exhibit very poor strength and it is
difficult to process the aerogel to have various thicknesses and
shapes, there is a predetermined limitation in application to the
adiabatic material even though the aerogel has an excellent
adiabatic characteristic, and in the case where the aerogel and
other reactant are mixed, there are problems in that since a
solvent or a solute permeates an inside of the aerogel to increase
viscosity of a compound and thus make mixing unfeasible, it is
difficult to perform complexation of the aerogel with the other
material or use the aerogel after mixing with the other material,
and a characteristic of the porous aerogel is not exhibited.
[0052] On the other hand, in the adiabatic coating composition of
various embodiments, the polyamideimide resin exists while being
dispersed in the high boiling point organic solvent or aqueous
solvent and the aerogel exists while being dispersed in the low
boiling point organic solvent, and thus a solvent dispersion phase
of the polyamideimide resin and a solvent dispersion phase of the
aerogel do not agglomerate but may be uniformly mixed, and the
adiabatic coating composition may have a homogeneous
composition.
[0053] Moreover, since the high boiling point organic solvent or
aqueous solvent and the low boiling point organic solvent are not
easily mutually dissolved or mixed, the polyamideimide resin and
the aerogel are mixed while the polyamideimide resin is dispersed
in the high boiling point organic solvent or aqueous solvent and
the aerogel is dispersed in the low boiling point organic solvent,
to form the coating composition, and thus direct contact between
the polyamideimide resin and the aerogel may be minimized until the
adiabatic coating composition of the various embodiments is applied
and dried, and the polyamideimide resin may be prevented from
permeating the inside of the aerogel or the pore or being
impregnated in the aerogel or the pore.
[0054] Further, since the low boiling point organic solvent has
predetermined affinity with the high boiling point organic solvent
or aqueous solvent, the low boiling point organic solvent may serve
to materially mix the aerogel dispersed in the low boiling point
organic solvent and the polyamideimide resin dispersed in the high
boiling point organic solvent or aqueous solvent and thus uniformly
distribute the aerogel and uniformly distribute the polyamideimide
resin in the high boiling point organic solvent or aqueous
solvent.
[0055] Accordingly, in the adiabatic coating layer obtained from
the adiabatic coating composition of the various embodiments,
physical properties of the aerogel may be secured at the same level
or more, and the aerogel may be more uniformly dispersed in the
polyamideimide resin to implement improved adiabatic
characteristics together with high mechanical properties and heat
resistance.
[0056] That is, as described above, in the adiabatic coating layer
obtained from the adiabatic coating composition of the various
embodiments, since physical properties and the structure of the
aerogel may be maintained at the same level, the adiabatic coating
layer may secure high mechanical properties and heat resistance
while having lower thermal conductivity and lower density, and may
be applied to the internal combustion engine to reduce heat energy
emitted to the outside and thus improve efficiency of the internal
combustion engine and fuel efficiency of the vehicle.
[0057] Moreover, the adiabatic coating layer obtained from the
adiabatic coating composition of the various embodiments may be
applied to a portion of the exhaust valve or the entire exhaust
valve, which is a part of the internal combustion engine, to secure
high temperature durability by reducing a valve temperature,
without using the very costly high heat resistant material where
the nickel (Ni) content is increased.
[0058] Herein, the adiabatic coating layer, as illustrated in FIG.
1, may be applied to the face portion 13 coming into contact with
the flame of the combustion chamber, the neck portion 15 coming
into contact with the exhaust gas, and both the face portion 13 and
the neck portion 15.
[0059] Meanwhile, the adiabatic coating composition of the various
embodiments may be formed by mixing the polyamideimide resin
dispersed in the high boiling point organic solvent or aqueous
solvent and the aerogel dispersed in the low boiling point organic
solvent as described above.
[0060] The mixing method is not largely limited, and any typically
known physical mixing method may be used. For example, there may be
a method of manufacturing a coating composition (coating solution)
by mixing two kinds of solvent dispersion phases, adding a zirconia
bead thereto, and performing ball milling under a condition of a
temperature of room temperature and normal pressure at a speed of
100 to 500 rpm. However, the method of mixing the solvent
dispersion phases of the polyamideimide resin and the aerogel is
not limited to the aforementioned example.
[0061] The adiabatic coating composition of various embodiments may
provide the adiabatic material, an adiabatic structure, and the
like, which may be maintained over a long period of time in the
internal combustion engine to which a repeated high temperature and
high pressure condition is applied, and specifically, the adiabatic
coating composition of various embodiments may be used in coating
of an internal surface of the internal combustion engine or parts
of the internal combustion engine, and as described above, may be
used in coating of the face portion and/or the neck portion of the
exhaust valve.
[0062] An example of the polyamideimide resin, which may be
included in the adiabatic coating composition of the various
embodiments, is not largely limited, but the polyamideimide resin
may have a weight average molecular weight of 3,000 to 300,000, or
4,000 to 100,000.
[0063] If the weight average molecular weight of the polyamideimide
resin is very small, it may be difficult to sufficiently secure
mechanical properties, heat resistance, and an adiabatic property
of a coating layer, a coating film, or a coating membrane obtained
from the adiabatic coating composition, and a polymer resin may
easily permeate the inside of the aerogel.
[0064] Further, if the weight average molecular weight of the
polyamideimide resin is very large, uniformity or homogeneity of
the coating layer, the coating film, or the coating membrane
obtained from the adiabatic coating composition may deteriorate,
dispersibility of the aerogel in the adiabatic coating composition
may be reduced or a nozzle and the like of a coating device may be
clogged when the adiabatic coating composition is applied, a
heat-treating time of the adiabatic coating composition may be
prolonged, and a heat-treating temperature may be increased.
[0065] A typical aerogel known in the art may be used as the
aforementioned aerogel, and specifically, the aerogel of components
including silicon oxide, carbon, polyimide, metal carbide, or a
mixture of two or more kinds thereof may be used. The aerogel may
have a specific surface area of 100 cm.sup.3/g to 1,000 cm.sup.3/g,
or 300 cm.sup.3/g to 900 cm.sup.3/g.
[0066] The adiabatic coating composition may include the aerogel in
a content of 5 to 50 parts by weight or 10 to 45 parts by weight
based on 100 parts by weight of the polyamideimide resin. A weight
ratio of the polyamideimide resin and the aerogel is a weight ratio
of solids other than the dispersion solvent.
[0067] If the content of the aerogel based on the polyamideimide
resin is very small, it may be difficult to reduce thermal
conductivity and density of the coating layer, the coating film, or
the coating membrane obtained from the adiabatic coating
composition, it may be difficult to secure a sufficient adiabatic
property, and heat resistance of the adiabatic membrane
manufactured from the adiabatic coating composition may be
reduced.
[0068] Further, if the content of the aerogel based on the polymer
resin is very large, it may be difficult to sufficiently secure
mechanical properties of the coating layer, the coating film, or
the coating membrane obtained from the adiabatic coating
composition, cracks may be generated in an adiabatic membrane
manufactured from the adiabatic coating composition, or it may be
difficult to maintain a strong coat form of the adiabatic
membrane.
[0069] The solid content of the polyamideimide resin in the high
boiling point organic solvent or aqueous solvent is not largely
limited, but the solid content may be 5 wt % to 75 wt % in
consideration of uniformity or physical properties of the adiabatic
coating composition.
[0070] Further, the solid content of the aerogel in the low boiling
point organic solvent is not largely limited, but the solid content
may be 5 wt % to 75 wt % in consideration of uniformity or physical
properties of the adiabatic coating composition.
[0071] As described above, since the high boiling point organic
solvent or aqueous solvent and the low boiling point organic
solvent are not easily mutually dissolved or mixed, direct contact
between the polyamideimide resin and the aerogel may be minimized
until the adiabatic coating composition of the various embodiments
is applied and dried, and the polyamideimide resin may be prevented
from permeating the inside of the aerogel or the pore or being
impregnated in the aerogel or the pore.
[0072] Specifically, a boiling point difference between the high
boiling point organic solvent and the low boiling point organic
solvent may be 10.degree. C. or more, 20.degree. C. or more, or 10
to 200.degree. C. As the high boiling point organic solvent, an
organic solvent having the boiling point of 110.degree. C. or more
may be used.
[0073] Specific examples of the high boiling point solvent may
include anisole, toluene, xylene, methyl ethyl ketone, methyl
isobutyl ketone, ethyleneglycol monomethylether, ethyleneglycol
monoethylether, ethyleneglycol monobutylether, butyl acetate,
cyclohexanone, ethyleneglycol monoethylether acetate (BCA),
benzene, hexane, DMSO, N,N'-dimethylformamide, or a mixture of two
or more kinds thereof.
[0074] As the low boiling point organic solvent, an organic solvent
having the boiling point of less than 110.degree. C. may be
used.
[0075] Specific examples of the low boiling point organic solvent
may include methyl alcohol, ethyl alcohol, propyl alcohol, n-butyl
alcohol, iso-butyl alcohol, tert-butyl alcohol, acetone, methylene
chloride, ethylene acetate, isopropyl alcohol, or a mixture of two
or more kinds thereof.
[0076] Meanwhile, specific examples of the aqueous solvent may
include water, methanol, ethanol, ethyl acetate, or a mixture of
two or more kinds thereof.
[0077] On the other hand, according to various embodiments of the
present invention, an adiabatic coating layer including a
polyamideimide resin and an aerogel dispersed in the polyamideimide
resin and having thermal conductivity of 0.60 W/m or less may be
provided.
[0078] The present inventors manufactured the adiabatic coating
layer, which could secure high mechanical properties and heat
resistance while having low thermal conductivity and low density,
and be applied to an internal combustion engine to reduce heat
energy emitted to the outside and thus improve efficiency of the
internal combustion engine and fuel efficiency of a vehicle, by
using the aforementioned adiabatic coating composition of the
various embodiments.
[0079] Moreover, the present inventors manufactured the adiabatic
coating layer, which could secure high temperature durability by
using the aforementioned adiabatic coating composition of the
various embodiments to reduce an exhaust valve temperature, without
using the very costly high heat resistant material where the nickel
(Ni) content was increased.
[0080] In the adiabatic coating layer, the aerogel is uniformly
dispersed over an entire region of the polyamideimide resin, and
thus physical properties implemented from the aerogel, for example,
low thermal conductivity and low density may be more easily
secured, and a characteristic revealed from the polyamideimide
resin, for example, high mechanical properties, heat resistance,
and the like, may be implemented at the same level or more as the
case where only the polyamideimide resin is used.
[0081] The adiabatic coating layer may have low thermal
conductivity and the high thermal capacity, and specifically, the
adiabatic coating layer may have thermal conductivity of 0.60 W/m
or less, 0.55 W/m or less, or 0.60 W/m to 0.200 W/m, and the
adiabatic coating layer may have the thermal capacity of 1,250
KJ/m.sup.3 K or less or 1,000 to 1,250 KJ/m.sup.3 K.
[0082] Meanwhile, as described above, since the adiabatic coating
composition of the various embodiments includes the polyamideimide
resin dispersed in the high boiling point organic solvent or
aqueous solvent and the aerogel dispersed in the low boiling point
organic solvent, direct contact between the polyamideimide resin
and the aerogel may be minimized until the coating composition is
applied and dried, and thus the polyamideimide resin may not
permeate the inside of the aero gel or the pore included in the
finally manufactured adiabatic coating layer or not be impregnated
in the aerogel or the pore.
[0083] Specifically, the polyamideimide resin may not substantially
exist in the aerogel dispersed in the polyamideimide resin, and for
example, the polyamideimide resin may exist in a content of 2 wt %
or less or 1 wt % or less in the aerogel.
[0084] Further, in the adiabatic coating layer, the aerogel may
exist while being dispersed in the polyamideimide resin, and in
this case, the outside of the aerogel may be in contact with or
combined with the polyamideimide resin, but the polyamideimide
resin may not exist in the aerogel. Specifically, the
polyamideimide resin may not exist at a depth corresponding to 5%
or more of a longest diameter from a surface of the aerogel
included in the adiabatic coating layer.
[0085] Since the polyamideimide resin does not permeate the inside
of the aerogel or the pore or is not impregnated in the aerogel or
the pore, the aerogel may have the same level of porosity before
and after the aerogel is dispersed in the polyamideimide resin, and
specifically, each aerogel included in the adiabatic coating layer
may have porosity of 92% to 99% while being dispersed in the
polyamideimide resin.
[0086] The adiabatic coating layer of the various embodiments may
provide an adiabatic material, an adiabatic structure, and the
like, which may be maintained over a long period of time in the
internal combustion engine to which a repeated high temperature and
high pressure condition is applied, and specifically, the adiabatic
coating layer of the various embodiments may be formed on the
internal surface of the internal combustion engine or the exhaust
valve that is a part of the internal combustion engine.
[0087] A thickness of the adiabatic coating layer of the various
embodiments may be determined according to an application field or
position, or required physical properties, and for example, may be
50 .mu.m to 500 .mu.m.
[0088] The adiabatic coating layer of the various embodiments may
include the aerogel in a content of 5 to 50 parts by weight or 10
to 45 parts by weight based on 100 parts by weight of the
polyamideimide resin.
[0089] If the content of the aerogel based on the polyamideimide
resin is very small, it may be difficult to reduce thermal
conductivity and density of the adiabatic coating layer, it may be
difficult to secure a sufficient adiabatic property, and heat
resistance of the adiabatic coating layer may be reduced. Further,
if the content of the aerogel based on the polymer resin is very
large, it may be difficult to sufficiently secure mechanical
properties of the adiabatic coating layer, cracks of the adiabatic
coating layer may be generated, or it may be difficult to maintain
a strong coat form of the adiabatic membrane.
[0090] The polyamideimide resin may have a weight average molecular
weight of 3,000 to 300,000 or 4,000 to 100,000.
[0091] The aerogel may include one or more kinds of compounds
selected from the group consisting of silicon oxide, carbon,
polyimide, and metal carbide.
[0092] The aerogel may have a specific surface area of 100
cm.sup.3/g to 1,000 cm.sup.3/g.
[0093] A specific content of the polyamideimide resin and the
aerogel includes the aforementioned content of the adiabatic
coating composition of the various embodiments.
[0094] Meanwhile, the adiabatic coating layer of the various
embodiments may be obtained by drying the adiabatic coating
composition of the various embodiments. A device or a method, which
may be used in drying the adiabatic coating composition of the
various embodiments, is not largely limited, and a spontaneous
drying method at a temperature of room temperature or more, a
drying method by heating to a temperature of 50.degree. C. or more,
or the like may be used.
[0095] For example, the adiabatic coating composition of the
various embodiments may be applied on a coating target, for
example, the internal surface of the internal combustion engine or
an external surface of parts of the internal combustion engine, and
semi-dried at a temperature of 50.degree. C. to 200.degree. C. one
or more times, and the semi-dried coating composition may be
completely dried at a temperature of 200.degree. C. or more to form
the adiabatic coating layer. However, a specific manufacturing
method of the adiabatic coating layer of the various embodiments is
not limited thereto.
[0096] The present invention will be described in more detail in
the following Examples. However, the following Examples are set
forth to illustrate the present invention but are not to be
construed to limit the present invention.
Examples 1 to 3
(1) Manufacturing of Adiabatic Coating Composition
[0097] The porous silica aerogel (specific surface area: about 500
cm.sup.3/g) dispersed in ethyl alcohol and the polyamideimide resin
(products manufactured by Solvay SA, weight average molecular
weight: about 11,000) dispersed in xylene were injected into the 20
g reactor, the zirconia bead was added thereto (440 g), and ball
milling was performed under the room temperature and normal
pressure condition at the speed of 150 to 300 rpm to manufacture
the adiabatic coating composition (coating solution).
[0098] In this case, the weight ratio of the porous silica aerogel
based on the polyamideimide resin is the same as the matter
described in the following Table 1.
(2) Forming of Adiabatic Coating Layer
[0099] The obtained adiabatic coating composition was applied on a
part for a vehicle engine by a spray coating method. In addition,
the adiabatic coating composition was applied on the part, primary
semi-drying was performed at about 150.degree. C. for about 10
minutes, the adiabatic coating composition was re-applied, and
secondary semi-drying was performed at about 150.degree. C. for
about 10 minutes. After secondary semi-drying, the adiabatic
coating composition was applied again, and complete drying was
performed at about 250.degree. C. for about 60 minutes to form the
adiabatic coating layer on the part. In this case, the thickness of
the formed coating layer is the same as the matter described in the
following Table 1.
Comparative Example 1
[0100] The solution (PAI solution) of the polyamideimide resin
(products manufactured by Solvay SA, weight average molecular
weight: about 11,000) dispersed in xylene was applied on a part for
a vehicle engine by the spray coating method.
[0101] In addition, the PAI solution was applied on the part,
primary semi-drying was performed at about 150.degree. C. for about
10 minutes, the PAI solution was re-applied, and secondary
semi-drying was performed at about 150.degree. C. for about 10
minutes. After the secondary semi-drying, the PAI solution was
applied again, and complete drying was performed at about
250.degree. C. for about 60 minutes to form the adiabatic coating
layer on the part. In this case, the thickness of the formed
coating layer is the same as the matter described in the following
Table 1.
Comparative Example 2
Manufacturing of Coating Composition
[0102] The porous silica aerogel (specific surface area: about 500
cm.sup.3/g) and the polyamideimide resin (products manufactured by
Solvay SA, weight average molecular weight: about 11,000) dispersed
in xylene were injected into the 20 g reactor, the zirconia bead
was added thereto (440 g), and ball milling was performed under the
room temperature and normal pressure condition at the speed of 150
to 300 rpm to manufacture the coating composition (coating
solution).
[0103] In this case, the weight ratio of the porous silica aerogel
based on the polyamideimide resin is the same as the matter
described in the following Table 1.
(2) Forming of Adiabatic Coating Layer
[0104] The coating layer having the thickness of about 200 .mu.m
was formed by the same method as Example 1.
Experimental Example 1
Measurement of Thermal Conductivity
[0105] Thermal conductivity of the coating layers on the parts
obtained in the Examples and the Comparative Examples was measured
on the basis of ASTM E1461 under the room temperature and normal
pressure condition using the laser flash method by the thermal
diffusion measuring method.
[0106] Experimental Example 2:
[0107] Measurement of Thermal Capacity
[0108] The thermal capacity was confirmed by measuring specific
heat of the coating layers on the parts obtained in the Examples
and the Comparative Examples on the basis of ASTM E1269 under the
room temperature condition using the DSC device and using sapphire
as a reference.
TABLE-US-00001 TABLE 1 Content of aerogel based on 100 parts
Thermal Thermal by weight of Thickness of conductivity capacity of
PAI resin (parts coating layer of coating coating layer by weight)
(.mu.m) layer [W/m] [KJ/m.sup.3 K] Example 1 15 120 0.54 1216
Example 2 20 200 0.331 1240 Example 3 40 200 0.294 1124 Comparative
-- 200 0.56 1221 Example 1
[0109] As described in Table 1, it was confirmed that the adiabatic
coating layer obtained in Examples 1 to 3 had the thermal capacity
of 1240 KJ/m.sup.3 K or less and thermal conductivity of 0.54 W/m
or less in the thickness of 120 to 200 .mu.m. Accordingly, the
adiabatic coating layer obtained in Examples 1 to 3 may be applied
to coating of the parts of the internal combustion engine to reduce
heat energy emitted to the outside and thus improve efficiency of
the internal combustion engine and fuel efficiency of the
vehicle.
[0110] Moreover, the adiabatic coating layer obtained from Examples
1 to 3 may be applied to coating of a portion of the exhaust valve
or the entire exhaust valve to secure high temperature durability
by reducing a valve temperature, without using the very costly high
heat resistant material where the nickel (Ni) content is
increased.
[0111] Further, as illustrated in FIG. 2, it can be confirmed that
in the adiabatic coating layer manufactured in Example 1, the
polyamideimide resin does not permeate the inside of the aerogel
and almost 92% or more of the pores in the aerogel are
maintained.
[0112] On the other hand, in the coating layer manufactured in
Comparative Example 2, as illustrated in FIG. 3, the polyamideimide
resin permeated the inside of the aerogel, and thus the pores were
hardly observed.
[0113] According to the aforementioned exhaust valve 100 for the
engine according to the various embodiments of the present
invention, it is possible to ensure high temperature durability and
reduce heat energy emitted to the outside by applying the adiabatic
coating layer capable of securing high mechanical properties and
heat resistance while having low thermal conductivity and the low
volume thermal capacity, thereby improving efficiency of an engine
and fuel efficiency of a vehicle.
[0114] Further, in the various embodiments of the present
invention, it is possible to secure high temperature durability and
reduce a manufacturing cost by applying the adiabatic coating layer
to reduce a valve temperature, without using a very costly high
heat resistant material (inconel and the like) where a nickel (Ni)
content is increased.
[0115] The foregoing descriptions of specific exemplary embodiments
of the present invention have been presented for purposes of
illustration and description. They are not intended to be
exhaustive or to limit the invention to the precise forms
disclosed, and obviously many modifications and variations are
possible in light of the above teachings. The exemplary embodiments
were chosen and described in order to explain certain principles of
the invention and their practical application, to thereby enable
others skilled in the art to make and utilize various exemplary
embodiments of the present invention, as well as various
alternatives and modifications thereof. It is intended that the
scope of the invention be defined by the Claims appended hereto and
their equivalents.
* * * * *